The common treatment for renal failure is hemodialysis treatment or peritoneal dialysis treatment. Both treatments utilize the diffusion of liquid through a semipermeable membrane. In the case of hemodialysis the membrane is in a dialyzer external to the patient, so that blood is withdrawn from the patient's vascular system and passed across the membrane while dialysis solution is passed across the other side of the membrane. Impurities in the blood are drawn through the membrane by osmotic pressure on the membrane and are disposed of in the discarded dialysis solution. In the case of peritoneal dialysis, the semipermeable membrane is the patient's peritoneal membrane. Dialysis solution is introduced into and retained for a period of time in the peritoneal cavity, and impurities in the blood migrate through the peritoneal membrane and into the dialysis solution. The dialysis solution with the impurities is then withdrawn from the peritoneal cavity and discarded.
Both hemodialysis and peritoneal dialysis require significant amounts of dialysis solution, sometimes called dialysate. Common dialysates are primarily water, but with low ionic concentrations of dissolved sodium, potassium, calcium, magnesium, chloride, acetate, glucose and bicarbonate. The proportions of these and other compounds depends on a variety of factors. Regardless of the exact concentrations and relative proportions of the dissolved compounds, the main material in all dialysates is water.
Dialysis solutions have in the past been premixed and prepackaged in a variety of mixes and sizes, so that the patient or the medical professional simply selects the desired size and mix of dialysate, makes the appropriate tubing connections to the prepackaged dialysates and to the patient and the dialysis machine, and then commences the procedure.
Although this practice of prepackaging dialysate was convenient, it was somewhat expensive and cumbersome. Effective dialysis treatment generally requires several dialysis sessions per week, and each session requires at least several liters (and perhaps several dozen liters) of dialysate. Therefore, a single patient could go through hundreds of liters of dialysate a month. Multiplied by a number of dialysis patients, a single dialysis facility would use many thousands of liters of solution a month. This large quantity of dialysate was expensive and inconvenient to store, and was also expensive to ship from a manufacturing plant to dialysis facilities throughout the world.
The expense and inconvenience of shipping and storing large quantities of dialysis solution was partially overcome by the introduction and widespread acceptance of granulated solid dialysate concentrate. Such concentrates are simply dry mixes in solid granulated form, which are dissolved in water at the treatment site and then the water with the dissolved ions becomes the dialysate to be administered to the patient. This greatly reduces the volume and especially the weight of the material that is shipped from manufacturing plants to dialysis treatment facilities, thereby reducing the cost of shipping and the cost and inconvenience of storage. For purposes of the claims herein, "granulated" is intended to include powders or any other loose solid form.
A drawback to the use of dialysate concentrates is that they are not conveniently prepackaged and ready for use. While prepackaged liquid dialysate could simply be attached to the tubing set and used, dialysate concentrate must be measured and mixed with water. This requires a measurement system for both the dialysate concentrate and the water, a mixing system which ensures complete dissolving of the concentrate in the water, and a storage container for the dialysate once the measurement and mixing is completed so that the dialysate can then be used. Manufacturers commonly package the concentrate in small fix-sized packages to assist in the measurement process, but the treatment facilities often open the small packages and combine them into large containers, thereby once again requiring the measurement process.
Accordingly, there is a need for a system for packaging and using dialysate concentrate which preserves the advantages of dialysate concentrate in reducing shipping and storing costs, but also is simple to use and requires little or no measurement, mixing or transfer to a separate container.